Twitter button on my site show 0, but in the test environment is correct … and the code for the button is identical!
The page I link in the data-url is a private page, so if I request the page the result is to be redirect to login page.
This can be a problem?

Yes, the infrastructure that powers the Tweet Button will make requests to your site to verify that a Tweet Button actually exists before counting tweets for you. If it can’t get to your server and verify the Tweet Button is there, it won’t count the page.